1. Field of the Invention
The present invention relates to a signal output device. The invention also relates to a sheet material detecting device, more particularly to a sheet material detecting device which detects the type of a given sheet by applying an impact to the sheet.
2. Related Background Art
Some of the image formation devices which have come into use in recent years, including copying machines, printers and facsimile machines, form images on a wide variety of sheets differing in material, thickness and other attributes, including calendered paper, coated paper and transparent resin film. Any such device, when it is to form an image on any type of these diverse sheets, has to match the operating conditions including the feeding speed and the fixation temperature to the properties of the sheet material, and conventional image formation devices use a sheet material detecting device, integrated with or separately disposed from them, for identifying the sheet material.
Such a sheet material detecting device is disclosed in, for instance, in the U.S. Pat. No. 6,097,497. According to the technique proposed in the patent, the sheet itself is marked in advance with a code consisting of some numeral or symbol and representing information on the sheet, a sensor disposed in a printer reads the code, and the printer uses the code information so read to optimize the printing mode (hereinafter referred to as the marking system). However, such a marking system can be of no use in detecting the material of any uncoded sheet.
Another sheet material detecting device which stops the feeding of a sheet every time it distinguishes the material of the sheet, especially if it is built into a structure such as an image formation device, may affect the performance of the structure.
An object of the present invention is to provide a signal output device, method or the like which can supply information on sheet material even if the sheet is not coded in advance.
Another object of the invention is to provide a sheet material detecting device capable of identifying the material of a sheet while feeding the sheet.